Techno-economic evaluation of demilitarized TiCl₄ recycling processes

Abstract

Demilitarization has become a critical field of study in South Africa over the last decade. With the focus of reusing or recycling all components with potential values, hazardous environmental impacts can be drastically reduced or even eliminated. The aim of this study was to analyse potential recycling solutions of demilitarized titanium tetrachloride (TiCl₄), which had been obtained by the preceding demilitarization of smoke mortars. The demilitarized TiCl₄ was quantified to be approximately 42 ton, distributed into smaller batches and processed over a period of six years. This analysis was performed by means of a detailed techno-economic evaluation. The three main potential recycling considerations were titanium (Ti) sponge production, titanium dioxide (TiO₂) pigment production and a vaporization process to obtain TiCl₄ that can be reused in the manufacturing of new smoke mortars.

Prior to process configuration, received samples of demilitarized TiCl₄ were analysed to identify and quantify common impurities and determine initial feed quality from the demilitarization stock. These processes were then simulated on Aspen Plus™ as part of the technical assessment. Ti sponge was produced by implementation of the Kroll process while TiO₂ pigment was produced through the chloride process and reusable TiCl₄ was obtained by a two-step boiling process of demilitarized TiCl₄. Simulation results indicate that all three processes are technically executable and correspond with independent theoretical calculations. Verification of both sets of results with existing stipulations indicates that produced sponge and pigment conform to the American Society of Testing and Materials (ASTM) standards and recovered TiCl₄ complies with industrial requirements for mortar manufacturing applications.